Post ductal coarctation of aorta | Frequently Asked Medical PG topics

In post ductal coarctation of aorta, collaterals to the lower limb are formed by all except 

A. Vertebral artery 
B. Suprascapular artery
C. Posterior Intercostal artery 
D. Internal Thoracic arter

Ans. A. Vertebral artery 

Explanation: 

1. Coarctation of the aorta, or aortic coarctation, is a congenital condition whereby the aorta narrows in the area where the ductus arteriosus ligamentum arteriosum after regression.  inserts 

2. There are three types: 

a.  Preductalcoarctation: The narrowing is proximal to the ductus arteriosus. If severe, blood 

flow to the aorta distal to the narrowing supplying lower body.  is dependent on a patent ductus arteriosus, and hence its closure can be life-threatening. Preductal coarctation results when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart, leading to hypoplastic development of the aorta. This is the type seen in approximately 5% of infants with Turner Syndrome. 

b.  Ductal coarctation: The narrowing occurs at the insertion of the ductus arteriosus. This kind usually appears when the ductus arteriosus closes. 

3. Postductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus. an extensive collateral circulation develops involving the branches of subclavian &axillarvarteries with the distal arteries given by aorta e.g., posterior intercostal arteries, . But the vertebral artery is not playing significant role in this collateral circulation. Even with an open ductus arteriosus blood flow to the lower body can be impaired. This type is most common in adults. It is associated with notching of the ribs, hypertension in the upper extremities, and weak pulses in the lower extremities. This type is most likely the result of muscular ductal ductus arteriosis.  extends into the aorta during fetal life. 

4. The purpose of this extensive collateral circulation is to send blood into the distal branches of the aorta namely — posterior intercostalsand iliac arteries. 

5. The enlarged branches of subclavian artery are suprascapular, costocervical trunk first &second posterior intercostals.  and the internal thoracic arteries. 

6. The branches of axillary artery involved are thoraco-acromial, lateral thoracic and the subscapular, 

7. The internal thoracic arteries give anterior intercostal arteries and the superior epigastric arteries. Anterior intercostals carry blood to the posterior intercostalsand thence into the descending aorta.

8. The superior epigastric artery anastomoses with the inferior epigastric in the rectus sheath.  and sends blood into the external iliac artery and thence mainly towards the lower limb. 

9. High vascularity is observed in the anterior thoracic wall as well as over the posterior thoracic wall, especially in the interscapular area. 

10. Radiographic evidence of ‘Rib notching’ is seen in the inferior margins of the ribs due to greatly enlarged posterior intercostal arteries.